Add option for FOSS contribution payments (#730)

* First commit

* Use subscription flow for monetary contributions

* Removed only part of the SPAN

* Localize Stripe payments message

* More localization of contribution strings

* Missed two billing to payment changes

* Fix tests

* Localization of "Open Demo" strings

* Fix grammar error

* Update for consistency

* Localize CTA

* More localilzation strings

app/models/subscription.rb

@@ -1,5 +1,5 @@
 class Subscription < ApplicationRecord
-  TRIAL_DAYS = 14
+  TRIAL_DAYS = 45
 
   belongs_to :family
 
@@ -28,11 +28,11 @@ class Subscription < ApplicationRecord
   def name
     case interval
     when "month"
-      "Monthly Plan"
+      "Monthly Contribution"
     when "year"
-      "Annual Plan"
+      "Annual Contribution"
     else
-      "Free trial"
+      "Open demo"
     end
   end
 end